Improve empty group display.

Telegram/SourceFiles/history/history.cpp

@@ -586,6 +586,7 @@ HistoryItem *History::addNewToLastBlock(
 		applyMessageChanges(item, msg);
 	}
 	const auto result = addNewItem(item, newUnreadMessage);
+	checkForLoadedAtTop(result);
 	if (type == NewMessageLast) {
 		// When we add just one last item, like we do while loading dialogs,
 		// we want to remove a single added grouped media, otherwise it will
@@ -599,6 +600,22 @@ HistoryItem *History::addNewToLastBlock(
 	return result;
 }
 
+void History::checkForLoadedAtTop(not_null<HistoryItem*> added) {
+	if (peer->isChat()) {
+		if (added->isGroupEssential() && !added->isGroupMigrate()) {
+			// We added the first message about group creation.
+			_loadedAtTop = true;
+			addEdgesToSharedMedia();
+		}
+	} else if (peer->isChannel()) {
+		if (added->id == 1) {
+			_loadedAtTop = true;
+			checkJoinedMessage();
+			addEdgesToSharedMedia();
+		}
+	}
+}
+
 HistoryItem *History::addToHistory(const MTPMessage &msg) {
 	const auto detachExistingItem = false;
 	return createItem(msg, detachExistingItem);
@@ -2130,7 +2147,7 @@ auto History::computeChatListMessageFromLast() const
 	// about migration in the chats list and display the last
 	// non-migration message from the original legacy group.
 	const auto last = lastMessage();
-	if (!last || !last->isGroupEssential() || !last->isEmpty()) {
+	if (!last || !last->isGroupMigrate()) {
 		return _lastMessage;
 	}
 	if (const auto chat = peer->asChat()) {
@@ -2216,7 +2233,7 @@ void History::setFakeChatListMessageFrom(const MTPmessages_Messages &data) {
 		}
 	});
 	const auto last = lastMessage();
-	if (!last || !last->isGroupEssential() || !last->isEmpty()) {
+	if (!last || !last->isGroupMigrate()) {
 		// Last message is good enough.
 		return;
 	}
@@ -2239,7 +2256,7 @@ void History::setFakeChatListMessageFrom(const MTPmessages_Messages &data) {
 		return;
 	}
 	const auto item = owner().addNewMessage(*other, NewMessageExisting);
-	if (!item || (item->isGroupEssential() && item->isEmpty())) {
+	if (!item || item->isGroupMigrate()) {
 		// Not better than the last one.
 		return;
 	}
@@ -2732,19 +2749,37 @@ bool History::isEmpty() const {
 }
 
 bool History::isDisplayedEmpty() const {
+	if (!loadedAtTop() || !loadedAtBottom()) {
+		return false;
+	}
 	const auto first = findFirstNonEmpty();
 	if (!first) {
 		return true;
-	} else if (!first->data()->isGroupEssential()) {
-		return false;
-	} else if (const auto chat = peer->asChat()) {
-		// For legacy chats we want to show the chat with only first
-		// message about you creating the group as an empty chat with
-		// a nice information about the group features.
-		return chat->amCreator() && (findLastNonEmpty() == first);
-	} else {
+	}
+	const auto chat = peer->asChat();
+	if (!chat || !chat->amCreator()) {
 		return false;
 	}
+
+	// For legacy chats we want to show the chat with only
+	// messages about you creating the group and maybe about you
+	// changing the group photo as an empty chat with
+	// a nice information about the group features.
+	if (nonEmptyCountMoreThan(2)) {
+		return false;
+	}
+	const auto isChangePhoto = [](not_null<HistoryItem*> item) {
+		if (const auto media = item->media()) {
+			return (media->photo() != nullptr) && !item->toHistoryMessage();
+		}
+		return false;
+	};
+	const auto last = findLastNonEmpty();
+	if (first == last) {
+		return first->data()->isGroupEssential()
+			|| isChangePhoto(first->data());
+	}
+	return first->data()->isGroupEssential() && isChangePhoto(last->data());
 }
 
 auto History::findFirstNonEmpty() const -> Element* {
@@ -2769,6 +2804,21 @@ auto History::findLastNonEmpty() const -> Element* {
 	return nullptr;
 }
 
+bool History::nonEmptyCountMoreThan(int count) const {
+	Expects(count >= 0);
+
+	for (const auto &block : blocks) {
+		for (const auto &element : block->messages) {
+			if (!element->data()->isEmpty()) {
+				if (!count--) {
+					return true;
+				}
+			}
+		}
+	}
+	return false;
+}
+
 bool History::hasOrphanMediaGroupPart() const {
 	if (loadedAtTop() || !loadedAtBottom()) {
 		return false;

Telegram/SourceFiles/history/history.h

@@ -396,6 +396,7 @@ private:
 		return _buildingFrontBlock != nullptr;
 	}
 
+	void checkForLoadedAtTop(not_null<HistoryItem*> added);
 	void mainViewRemoved(
 		not_null<HistoryBlock*> block,
 		not_null<Element*> view);
@@ -439,6 +440,7 @@ private:
 
 	HistoryItem *lastAvailableMessage() const;
 	void getNextFirstUnreadMessage();
+	bool nonEmptyCountMoreThan(int count) const;
 
 	// Creates if necessary a new block for adding item.
 	// Depending on isBuildingFrontBlock() gets front or back block.

Telegram/SourceFiles/history/history_inner_widget.cpp

@@ -543,7 +543,8 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 	auto clip = e->rect();
 	auto ms = getms();
 
-	bool historyDisplayedEmpty = (_history->isDisplayedEmpty() && (!_migrated || _migrated->isDisplayedEmpty()));
+	const auto historyDisplayedEmpty = _history->isDisplayedEmpty()
+		&& (!_migrated || _migrated->isDisplayedEmpty());
 	bool noHistoryDisplayed = _firstLoading || historyDisplayedEmpty;
 	if (!_firstLoading && _botAbout && !_botAbout->info->text.isEmpty() && _botAbout->height > 0) {
 		if (clip.y() < _botAbout->rect.y() + _botAbout->rect.height() && clip.y() + clip.height() > _botAbout->rect.y()) {
@@ -561,6 +562,8 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 		}
 	} else if (historyDisplayedEmpty) {
 		paintEmpty(p, width(), height());
+	} else {
+		_emptyPainter = nullptr;
 	}
 	if (!noHistoryDisplayed) {
 		auto readMentions = base::flat_set<not_null<HistoryItem*>>();

Telegram/SourceFiles/history/history_inner_widget.h

@@ -55,7 +55,6 @@ public:
 	void messagesReceivedDown(PeerData *peer, const QVector<MTPMessage> &messages);
 
 	TextWithEntities getSelectedText() const;
-	void paintEmpty(Painter &p, int width, int height);
 
 	void touchScrollUpdated(const QPoint &screenPos);
 
@@ -201,6 +200,8 @@ private:
 	std::unique_ptr<QMimeData> prepareDrag();
 	void performDrag();
 
+	void paintEmpty(Painter &p, int width, int height);
+
 	QPoint mapPointToItem(QPoint p, const Element *view) const;
 	QPoint mapPointToItem(QPoint p, const HistoryItem *item) const;
 

Telegram/SourceFiles/history/history_item.cpp

@@ -462,7 +462,7 @@ bool HistoryItem::canDelete() const {
 	}
 	auto channel = _history->peer->asChannel();
 	if (!channel) {
-		return !(_flags & MTPDmessage_ClientFlag::f_is_group_essential);
+		return !isGroupMigrate();
 	}
 
 	if (id == 1) {

Telegram/SourceFiles/history/history_item.h

@@ -137,6 +137,9 @@ public:
 	bool isGroupEssential() const {
 		return _flags & MTPDmessage_ClientFlag::f_is_group_essential;
 	}
+	bool isGroupMigrate() const {
+		return isGroupEssential() && isEmpty();
+	}
 	bool hasViews() const {
 		return _flags & MTPDmessage::Flag::f_views;
 	}

Telegram/SourceFiles/history/history_widget.cpp

@@ -6554,13 +6554,6 @@ void HistoryWidget::paintEvent(QPaintEvent *e) {
 		if (_pinnedBar && !_pinnedBar->cancel->isHidden()) {
 			drawPinnedBar(p);
 		}
-		if (_scroll->isHidden() && _history) {
-			p.setClipRect(_scroll->geometry());
-			_list->paintEmpty(
-				p,
-				width(),
-				height() - _field->height() - 2 * st::historySendPadding);
-		}
 	} else {
 		const auto w = st::msgServiceFont->width(lang(lng_willbe_history))
 			+ st::msgPadding.left()

Telegram/SourceFiles/history/view/history_view_service_message.cpp

@@ -557,7 +557,7 @@ void EmptyPainter::fillAboutGroup() {
 		text.setText(
 			st::serviceTextStyle,
 			content,
-			Ui::ItemTextServiceOptions());
+			Ui::NameTextOptions());
 	};
 	setText(_header, lang(lng_group_about_header));
 	setText(_text, lang(lng_group_about_text));
@@ -603,7 +603,7 @@ void EmptyPainter::paint(Painter &p, int width, int height) {
 		+ st::historyGroupAboutSkip * int(_phrases.size() - 1)
 		+ padding.bottom();
 	const auto bubbleLeft = (width - bubbleWidth) / 2;
-	const auto bubbleTop = (height - bubbleHeight) / 3;
+	const auto bubbleTop = (height - bubbleHeight) / 2;
 
 	ServiceMessagePainter::paintBubble(
 		p,